Resettable overload circuit breaker



Patented Dec. 27, 1949 EsErrAoLE OVERLOAD CIRCUIT BREAKER Richard C. Ingwersen, Jackson, Mich., assignor' 1 to Mechanical Products, Inc., Jackson, Mich.,--a corporation of Michigan I a I Application September 23,1944,'SerialNo.555,410'

2 Claims. (01. 200116) The present invention relates to improvements in resettable circuit breakers for electrical circuits, being particularly concerned with circuits in the order of to 50 amperes.

One of the objects of the present invention is to provide an inexpensive resettable circuit breaker so constructed as to be substituted withoutichange for the present-type of fusible link single use fuse.

Another object of the invention is to provide a a resettable circuit breaker which may be substituted for the present typeof fusible link fuse used in electrical circuits in the order of 10 to 50 amperes.

A further object of the invention is to provide a resettable circuit breaker of a simplified construction in which a bimetallic element is employed for holding the circuit closed and for opening the same upon overload.

These and other objects and advantages residing in the construction, combination and arrangement of parts will be more fully understood from the following specification and annexed claims.

In the drawing wherein one form of the invention is illustrated,

Fig. 1 is a vertical cross-sectional view of the fuse shown approximately double size,

Fig. 2 is a fragmentary view similar to Fig. 1 showing the position of the parts of the fuse following an overload, and

Fig. 3 is a vertical view of the improved resettable fuse shown in actual size.

Referring to the drawing, the circuit breaker Ill comprises a main body portion l2 preferably of molded insulating material, such as Bakelite or the like. Preferably the body I2 is made of two sections l4 and 16 divided along the line IS. The two halves are piloted upon integral pins 20 carried by the part 14 and extending in suitable recesses in the part l6. The lower portion of the body 12 is threaded as at 22 to permit screwing into position the conductive metal ferrule 24. The ferrule 24 has a threefold function; namely, that of assisting and holding the parts l4 and I6 in assembled relation, functioning as one of the contacts of the electric circuit and supporting the end plate 26 in position, as shown in Fig. 1.

The molded section 12 carries an insert 28 which is provided with a fiat end 30 to prevent rotation. The insert 28 functions to support the pin 32, which acts as a pivot for the L-shaped swinging contact support 34. As shown, the support 34 carries an insulated operating lever 36 which projects through an opening 38 to be operated from the outside of the fuse case to reset the same. The arm 46 carries a suitable contact 42. I 3": 2

The central contact 44 is supported in the plate 26 and has the additional function of holding the bimetal strip 46 in position through the nut 49 and threaded stud portion 50. The bimetal strip 46 is normally in theposition'shown in Fig. 1 supporting the contact support 34" as shown. As the bimetal strip 46 is electrically connected'to the contact 42, excessive electrical current passing therethroughwill develop suflicient'heat of resistance to stress the sametoward the position shown in Fig. 2, at which point thesupport 34 is no longer held innits horizontal position but is permitted to pivot around the pin 32 under stress of the spring 48, breaking-contact with the contact member 50, as shown in Fig. 2.

The contact 5|] is supported by a resilient conductor 52 which normally stresses the contact 56 in the position shown in Fig. 2. As is more clearly shown in Fig. 1, the conductor 52 is secured to the section I6 through a suitable rivet 54, with the lower end 56 of the conductor 52 electrically connected to the conductor 24 by being soldered as at 58.

In assembling the construction heretofore described, the conductive bimetal strip 46 is assembled to the end plate 26. A flexible conductor 60 is soldered at 62 to the upper end of the strip 46 and at its opposite end to a projecting tab 64 of the contact support 34. The support 34 is then assembled to the part [4 through the pin 32 and the spring 48 is connected as shown in Fig. 1. The parts [4 and I6 are then brought into assembled relation and the conductive metal ferrule 38 is screwed into position on the parts 14 and I6 and soldered as at 58.

The inherent resiliency of the bimetal strip 46, when at room temperature, tends to urge the same into the position indicated in Fig. 1. Thus, to set the fuse for operation with the contacts 42 and 50 in firm engagement, it is only necessary to move the member 36 to the position shown in Fig. 1, and the strip 46 will take the position shown supporting the contact support 34 in the position shown in Fig. 1. An excess flow of current through the strip 46 will result in its distortion, and if the overload continues the strip 46 will be distorted to the position as shown in Fig. 2, releasing the support 34 for pivotal movement under the stress of the spring 48, thus effecting the very rapid separation of the contacts 42 and 56. The fuse can thereafter be reset by merely urging the lever 36 from the position shown in Fig. 2 to that shown in Fig. 1.

Having thus described my invention, what I desire to secure by Letters Patent and claim is:

1. A resettable circuit breaker of the type described comprising a hollow body portion, a threaded conductor embracing the lower portion of said body as a ferrule, a fixed contact disposed in the upper portion of the said body and electrically connected to said ferrule, a central exterior conductor extending through the lower wall of said body, a bi-metallic member electrically connected to said central conductor and mounted on the inside of said lower wall and extending upwardly as a prop, a movable contact,

an L-shaped member upon one arm portion of which said movable contact is supported at its outer end in opposed relationship to said fixed contact, indicating and manually re-set means defined by the other arm portion of said member, the upper wall of said body having an opening defined therein through which said indicating and manually re-set means extends for manipulation and inspection, means constituting a pivotal connection between said body and said L-shaped member adjacent the intersection of said arm portions, a flexible electrical connector extending between said L-shaped member and said bimetallic member at a point adjacent the upper end of said bi-metallic member, said L-shaped member having ledge and clearance defining portions adjacent to said pivotal connection with which the upper end of said bi-metallic member cooperates to support said L-shaped member when engaging the ledge thereof as a prop with said contacts in engagement, said clearance being located between said pivotal connection and said ledge, said bi-metallic member in its unstressed position being positioned under said ledge, upon overload said bi-metallic member being stressed toward said pivotal connection and into said clearance to release said L-shaped member to pivotal movement about said pivotal connection, a tension spring connected at one end to said contact carrying arm portion of said L-shaped member and to the lower portion of said body at the opposite end, said L-shaped member, contacts, bi-metallic member, spring and pivot connection all being disposed in substantially the same general plane within the hollow portion of the said body and with respective movements thereof taking place in said general plane.

2. A resettable circuit breaker as defined in claim 1 wherein the said clearance is in the form of a notch directly adjacent to said pivotal connection.

RICHARD C. INGWERSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name: Date 1,256,692 Honsberger Feb. 19, 1918 1,485,580 Zimmerman Mar. 4, 1924 1,889,488 OBrien Nov. 29, 1932 2,044,448 Rivers June 16, 1936 2,147,754 Rivers Feb. 21, 1939 2,167,648 Grant Aug. 1, 1939 FOREIGN PATENTS Number Country Date 242,726 Great Britain Nov. 19, 1925 

